In conventional (current) HDDs, a magnetic signal is recorded by using a magnetic head (recording head) on a disk-like magnetic recording medium (continuous medium which is deposited with a magnetic material) on which a magnetic thin film made of fine crystal grains is formed. However, it is anticipated in the future that the crystal grain size will become smaller than 5 nm at the stage when recording density of HDDs will exceeds 1 terabit per 1 square inch (1 Tbit/inch2) by high integration, and it will make signal holding difficult due to thermal fluctuation.
As a countermeasure for that, in place of the conventional (current) medium (referred to as a non-patterned medium for discrimination), a technique for a patterned medium as disclosed in Japanese Patent Application Laid-Open Publication No. H03-22211 (Patent Document 1) is concerned. In a recording method using the patterned medium, a pattern having a track by a shape such as trench or dot is formed on the medium, and recording is performed on its separated magnetic material (recording unit). In this manner, the countermeasure is taken to reduction of reliability and noise from adjacent bits due to the thermal fluctuation mentioned above.
In a method of manufacturing this patterned medium, there are a method of partial non-magnetization with using a mask disclosed in International Publication No. WO03/019540 (Patent Document 2), a method of combining photolithography and etching disclosed in Japanese Patent Application Laid-Open Publication No. 2001-110050 (Patent Document 3), and others.
On the other hand, currently, in a magnetic recording method used for general HDDs, the magnetic material on the medium is subjected to magnetization reversal by a magnetic field (recording magnetic field) which is generated by the head (recording head), thereby performing signal recording. Therefore, the magnetic recording method has a feature that a physical size of a recording region (recording unit) corresponding to a recordable bit signal is determined by a magnetic field size of the head.
To realize a high recording density, a recording head having a magnetic field size corresponding to the recording density is required. That is, as an accuracy of the head, a recording magnetic field size is required to be properly small. Further, not only for the recording head, but also for a reproducing head for reading (reproducing) information which is recorded (written) on the medium, the same accuracy (that is, the reading magnetic field size being properly small) is required.
Note that, as for the head, generally, it is often a type (recording and reproducing head) of a single head to which both of a recording head function (writing element) and a reproducing head function (reading element) are provided. Of course, it is also possible to apply a configuration having different heads for writing and reading.
According to the foregoing, for example, as represented by a technique disclosed in Japanese Patent Application Laid-Open Publication No. H05-342527 (Patent Document 4), as a new structure of the recording and reproducing head, a technique example which makes the magnetic field size of the head small is proposed.
Further, in Japanese Patent Application Laid-Open Publication No. 2002-170348 (Patent Document 5), as a magnetic recording and reproducing method and a recording pattern formation method, a technique is disclosed in which, necessary parameters with respect to a plurality of track densities are recorded in advance, and then, the track density is set according to characteristics of a recording and reproducing head and a recording medium which have been measured after device assembly.